Although the Forrester's analysis is presented as a matrix of virtues, rather than a straight ranking, IBM shines for both the strength of its current offering, its market presence, and its strategy. IBM's SmartCloud for Social Business includes hosted versions of its IBM Connections enterprise social networking software, as well as tools for email, calendar, instant messaging, and other modes of online teamwork.

Microsoft actually owns two of the leading positions in this market by Forrester's ranking. Yammer is currently looking to maintain its momentum, as part of Microsoft, following a $1.3 billion acquisition. However, because the acquisition is so recent and the product lines have not yet begun to be integrated at any deep level, Forrester based its evaluation of Microsoft on Office365, which includes online document editing tools as well as cloud-hosted editions of SharePoint and Lync. In Forrester's analysis, a virtue of Office365 is that it "eases enterprises into the cloud by allowing IT leaders to pick which collaboration workloads move into the cloud and which remain on premises."

As a cloud-native product, Yammer's appeal is very different, more in tune with the consumerization of IT. A basic version of the Yammer service is offered for free, giving it mass-market appeal, while more serious enterprise users can convert their Yammer enterprise social networks to paid accounts. Although Yammer takes some heat from IT leaders over this freemium structure, Forrester said the service boasts "fairly sophisticated IT administration capabilities" for paying customers, "enabling abilities like multiple domain management, multiple access controls, and centralized provisioning and deprovisioning of users." Forrester expects Microsoft influence to "shore up Yammer's data center ops, global sales organization, and security and compliance capabilities."

"Microsoft will make Yammer stronger, and Yammer will make Microsoft stronger," said T.J. Keitt, lead author of the Forrester report. Whether the combination of the two will make for the strongest player, overall, is hard to say--particularly because Microsoft is likely to keep the two operations fairly separate "at least for the next couple of years," he said.

Software as a service is the clear No. 1 way enterprises consume cloud. InformationWeek's SaaS Innovation Survey reveals three tips to get the most from SaaS: Make it a popularity contest. Have an escape plan. And remember that identity is the new perimeter.